Hello again, Arduino forums. I've been working with phototransistors in the past few weeks and I just had a quick question about using many of them at once. I've been using a setup with a 22Kohm resistor that looks like this:

PWR------22K resistor----Analog in ----- phototransistor ---- GND

Is it possible to power a bunch of phototransistors simultaneously from the 5V pin on the Arduino? Like, oh, sixteen of them? Or do they each have to be hooked up to their own specific pins that provide power for each phototransistor? My wiring will be greatly simplified if it's possible to run just one pin with a resistor in front of it for power, though my gut tells me that this probably won't work.

Yes you can power many phototransistors from the +5v pin as KE7GKP says. But if you want to read 16 of them independently, you will need an external multiplexer, since the Arduino has only 6 analog inputs.

Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

My wiring will be greatly simplified if it's possible to run just one pin with a resistor in front of it for power, though my gut tells me that this probably won't work.

It won't work if you have only one resistor, but it will work with one 5V power supply (from the 5V power pin, not an Arduino output pin) and 16 separate resistors. If you think about it, with a single resistor, all the analog inputs will be connected together (draw out a circuit with, say, three phototransistors). As others have mentioned, you'll need an analog multiplexer to get 16 analog inputs into an Arduino.